| /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| /* ----------------------------------------------------------------------- |
| * |
| * Copyright 2009-2014 Intel Corporation; author H. Peter Anvin |
| * |
| * ----------------------------------------------------------------------- */ |
| |
| /* |
| * "Glove box" for BIOS calls. Avoids the constant problems with BIOSes |
| * touching registers they shouldn't be. |
| */ |
| |
| .code16 |
| .section ".inittext","ax" |
| .globl intcall |
| .type intcall, @function |
| intcall: |
| /* Self-modify the INT instruction. Ugly, but works. */ |
| cmpb %al, 3f |
| je 1f |
| movb %al, 3f |
| jmp 1f /* Synchronize pipeline */ |
| 1: |
| /* Save state */ |
| pushfl |
| pushw %fs |
| pushw %gs |
| pushal |
| |
| /* Copy input state to stack frame */ |
| subw $44, %sp |
| movw %dx, %si |
| movw %sp, %di |
| movw $11, %cx |
| rep; movsl |
| |
| /* Pop full state from the stack */ |
| popal |
| popw %gs |
| popw %fs |
| popw %es |
| popw %ds |
| popfl |
| |
| /* Actual INT */ |
| .byte 0xcd /* INT opcode */ |
| 3: .byte 0 |
| |
| /* Push full state to the stack */ |
| pushfl |
| pushw %ds |
| pushw %es |
| pushw %fs |
| pushw %gs |
| pushal |
| |
| /* Re-establish C environment invariants */ |
| cld |
| movzwl %sp, %esp |
| movw %cs, %ax |
| movw %ax, %ds |
| movw %ax, %es |
| |
| /* Copy output state from stack frame */ |
| movw 68(%esp), %di /* Original %cx == 3rd argument */ |
| andw %di, %di |
| jz 4f |
| movw %sp, %si |
| movw $11, %cx |
| rep; movsl |
| 4: addw $44, %sp |
| |
| /* Restore state and return */ |
| popal |
| popw %gs |
| popw %fs |
| popfl |
| retl |
| .size intcall, .-intcall |
